Current awareness of the importance of environmental factors such as diet in the etiology of human cancer has stimulated renewed interest in animal models for studying effects of diet on tumorigenesis. Diet can influence cancer in animals by affecting the initiation or subsequent preneoplastic stage of tumorigenesis, but it has less effect on tumor growth. Caloric restriction has a general inhibitory influence of tumorigenesis, Dietary fat, on the other hand, tends to promote tumorigenesis, but only certain types of tumors, such as mammary tumors, are affected. Both caloric restriction and dietary fat appear to act primarily during the preneoplastic stage, and their effects on hormone-dependent tumors may be mediated through changes in the hormonal environment. Variations in other dietary factors, such as protein, vitamins, or minerals, above the levels required for normal maintenance seem to have little influence on the genesis or growth of tumors.
Presented at the Conference on Nutrition in the Causation of Cancer, May 19 to 22, 1975, Key Biscayne, Fla. Original research reported in this paper was supported by Grant MT-1561 from the Medical Research Council of Canada.